The rise in the popularity of mobile phones and the fall in their prices has led the number of fixed-line telephone subscriptions to fall. The file Scandinavia contains the mobile phone and fixed telephone subscriptions per 100 inhabitants for Sweden from 2000 to 2016:

Year	Mobile phone sub- scriptions per 100 inhabitants	Fixed tele- phone sub- scriptions per 100 inhabitants	Year	Mobile phone sub- scriptions per 100 inhabitants	Fixed tele- phone sub- scriptions per 100 inhabitants
2000	71.75	68.19	2009	112.10	55.19
2001	80.67	66.92	2010	117.06	50.42

Year	Mobile phone sub- scriptions per 100 inhabitants	Fixed tele- phone sub- scriptions per 100 inhabitants	Year	Mobile phone sub- scriptions per 100 inhabitants	Fixed tele- phone sub- scriptions per 100 inhabitants
2002	89.11	65.57	2011	121.01	47.35
2003	98.32	64.57	2012	124.19	43.70
2004	97.71	63.27	2013	124.95	40.86
2005	100.72	62.34	2014	127.07	39.00
2006	105.61	60.98	2015	129.45	36.41
2007	110.41	60.02	2016	127.50	31.56
2008	108.41	57.79

a. Plot the data.

b. Compute a linear trend forecasting equation and plot the trend line.

c. Compute a quadratic trend forecasting equation and plot the trend line.

d. Compute an exponential trend forecasting equation and plot the trend line.

e. Which model is the most appropriate?

f. Using the most appropriate model, forecast the mobile phone subscriptions per 100 inhabitants for Sweden for 2018.